php based invoicing automation

Hi all, I would like to automate my invoicing procedure by creating pdf file from my already existing php application. I would like to issue an invoice out of two tables: 1-) Table called invoice; 2-) Table with items that will becomeinvoice items; The php script to de developed is to do the following: 1-) Give me a web page with a form so I selec the client and period I want to invoice for; 2-) The php script based on this will query on table billableitems for this particular client and display an invoice with invoicelines corresponding to billableitems table content ; 3-) It suggests validation and then we can press button to generate invoice; What is important at this stage is to get this quickly done. Please reply to this with specific answer to this. Please avoid copying/pasting replies to standard offers. Thanks in advance,